A new standard for site investigation, engineering, planning and execution of pipeline installation through horizontal directional drilling (HDD), has been published by DNV GL, the technical advisor to the oil and gas industry said.
The new standard, DNVGL-ST-F121, was created through a joint industry project and provides a series of minimum requirements and best practice for all phases, from site investigation, engineering and planning to execution of pipeline installation to reduce the risk associated to HDD crossings.
HDD is a construction method in the trenchless industry which provides significant improvements over traditional open cut methods for installing pipelines beneath obstructions such as rivers, highways and railroads. These include preservation of the ground surface of the construction site, minimal requirement for site preparation and reinstatement, and secure depth of cover.
The use of HDD installation techniques
has grown significantly over the last decades. The 21st Annual Underground Construction magazine HDD survey estimated in 2019 that contractors expected HDD to be applied to nearly half - 47% - of their projects.
However, HDD crossings are complex in nature and always very challenging. It is not uncommon to face problems during execution with significant impact on cost and schedule. The best way to overcome this is to ensure a proper investigation, engineering, planning and execution of all drilling-related activities.
Additionally, there are currently no methods for in situ repair of damaged pipelines installed by HDD, which makes it even more important to ensure the quality of pipeline design, construction and installation. The earlier potential risks and problems are identified in an HDD project, the better for the delivery of the project.
All these challenges led to a joint industry project to consolidate the knowledge and experience of HDD. Operators, EPC companies and drilling contractors were brought together for the first time, addressing not only the borehole stability and the drilling activities perspective but also the aspects related to the pipeline integrity as well.